Lug nuts

I have steel rims for winter so I needed nuts for them. Got my tires changed and they mounted the summer tires with the steel rim nuts. I got my bag out to check the nuts not used and they are not the size they should be. My old memory thought they should be 3/4" or 20 mm. Am I correct with my old memory.
Thanks

 

^OE alloy wheel lugnuts are 21mm socket size. 13/16" will usually be a tight fit.

Most "reduced acorn" lugnuts for steelies or aftermarket wheels are 3/4" or 19mm socket size. Haven't seen anything intended for 20mm.

 

Thanks very much for the answer, the 21 mm were in the bag which they did not use. I guess I better be changing nuts this morning.